264 



GENERAL BOTANY 



family (COMPOSITES) to whom it belongs, there is 

 a pappus of fine hairs. The grains of some grasses 

 have barbed awns that are most annoying to any one 

 who has to walk through tufts of them. The whole 

 flower head of XANTHIUM STRUMARIUM, a very 

 common Indian weed, attaches itself to animals by 

 hooked spines. Again the fruits of TRIBULUS TER- 

 RESTRIS, another common weed have short hard 

 spines which stick in the feet of animals and are 

 thus carried along, as are those of TRAPA, in which 

 the spines serve also to anchor the fruit while it 

 germinates. 



It is worthy of note that 

 all these fruits are achenes, 

 or have but few seeds even 

 when as in XANTHIUM the 

 spiny fruit is really a whole 

 flower head, such as in others 

 of its family, e.g. the Sun- 

 flower, contains a multitude 

 of florets, each with its own 

 ovary. The reason for this 

 is perhaps akin to that suggested for the similar 

 phenomenon in the case of fruits carried by wind. 



THE COLOURS OF FRUITS AND SEEDS 



7. It has been said that it is to attract insects, 

 for the purpose of cross-pollination, that petals are 

 coloured or flowers sweet-scented. Fruits and seeds 

 are also often specially coloured, not so commonly or 

 -brilliantly, perhaps, as flowers, but still much more 

 commonly and usefully than most people imagine. 



FIG. 66 



FRUIT OF TRAPA BISPINOSA 



Roxb. 



